Lockstitch sewing machine



Aug. 23, 1960 P. 0. PRYOR 2,949,873

LOCKSTITCH SEWING MACHINE Filed Nov. 27, 1957 15 Sheets-Sheet l m M", ,I

Aug. 23, 1960 P. o. PRYOR LOCKSTITCH SEWING MACHINE l5 Sheets-Sheet 2 Filed Nov. 27, 1957 NQE Aug. 23, 1960 P. D. PRYOR LOCKSTITCH SEWING MACHINE 15 Sheets-Sheet 3 Filed Nov. 27, 1957 FIG.6

Aug. 23, 1960 Filed NOV. 27, 1957 P. D. PRYOR LOCKSTITCH 'SEWING MACHINE 15 Sheets-Sheet 4 FIG] Aug. 23 1960 P. D. PRYOR 2,949,873

LOCKSTITCH SEWING MACHINE Filed Nov. 27, 1957 l5 Sheets-Sheet 5 FIG-.9

numuu] FIG.8

Aug. 23, 1960 P. D. PRYOR 2,949,873

LOCKSTITCH SEWING MACHINE Filed Nov. 27, 1957 15 Sheets-Sheet 6 FIG.I5

h n l will Aug- 23, 19 P. D. PRYOR 2,949,873

LOCKSTITCH SEWING MACHINE Filed Nov. 27, 1957 15 Sheets-Sheet '7 [hill Aug. 23, 1960 P. D. PRYOR LOCI/(STITCH SEWING MACHINE l5 Sheets-Sheet 8 Filed Nov. 27, 1957 Aug. 23, 1960 Filed Nov. 2'7, 195'? FIG. 20

P. D. PRYOR LOCKSTITCH SEWING MACHINE l5 Sheets-Sheet 9 IO N m [mum 0 Aug. 23, 1960 P. D. PRYOR LOCKSTITCH SEWING MACHINE l5 Sheets-Sheet 10 Filed Nov. 27, 1957 Aug. 23, 1960 Filed Nov. 27, 1957 P. D. PRYOR LOCKSTITCH SEWING MACHINE 15 Sheets-Sheet 11 Aug. 23, 1960 P. D. PRYOR LOCKSTITCH sswmc MACHINE 15 Sheets-Sheet 12 Filed NOV. 27, 1957 Aug. 23, 1960 Filed Nov. 27, 1957 P. D. PRYOR LOCKSTITCH SEWING MACHINE 15 Sheets-Sheet 13 IOI FIG. 25

Aug. 23, 1960 P. o. PRYOR 2,949,873

LOCKSTITCH SEWING MACHINE Filed Nov. 27, 1957 15 Sheets-Sheet 14 Aug. 23, 1960 P. D. PRYOR 2,949,873

LOCKSTITCH SEWING MACHINE Filed Nov. 27, 1957 15 Sheets-Sheet 15 United States LOCKSTITCH SEWING MACHINE Paul D; Pryor, Chicago, Ill., assignor to Union Special Machine Company, Chicago, 111., a corporation of Illinois Filed Nov. 27, 1951, S er. No.'699,219

14 Claims. 01. 112-184) vided on the bobbin carrier to prevent rotation of they latter with the rotary component. Means are also provided for turning the bobbin case holder through a small angle, at the proper time, counter to the frictional drag of the rotating hook. This is to open up a gap between the shoulders mentioned and thus permit the free passage of the needle thread loop around the bobbin carrier and between those shoulders which normally prevent rotation of the bobbin carrier with the rotary component.

The present invention is primarily concerned with the provision of improved means for turning the bobbin carrier, at the proper time, counter to the frictional drag of the rotary hook so that the shoulder on the bobbin carrier is shifted slightly away from the fixed shoulder carried by the frame of the machine to thus allow free passage of -a leg of the needle thread loop between these shoulders. Devices heretofore provided for this purpose have involved an oscillatory arm arranged to engage a triangular projection on the bobbin carrier for turning. the latter at the appropriate time counter to the frictional drag mentioned. Such devices have been subject to the objection that considerable noise iscreated as an incident to the striking of the oscillatory arm against the cooperating surface of the bobbin carrier. Also the constant striking of the oscillatory arm or finger against the surface on the bobbin carrier has led to excessive wear which has required frequent replacement of parts. Moreover, a limit has been imposed upon the speed of operation of the machine due to the inertia forces involved in oscillating the arm or finger mentioned.

The present invention largely overcomes these objections to prior devices and provides substantially noiseless means, which is subject to considerably less wear and capable of operation at considerably higher speeds than prior devices, for turning the bobbin carrier a sufficient distance to enable the free passage of the needle thread loop between the specified shoulders. For this purpose the turning of the bobbin carrier is effected by a rotating cam arranged to engage a projection on the bobbin carrier and turn the same counter to the frictional drag of the rotary hook, at the proper time. The arrangement is such, moreover, that a suitable clearance is provided at the appropriatetime between the constantly rotating cam and the projection on the bobbin ca e holde Q. h t e h e d l n x pa freely between these parts when required during the stitch forming cycle.

In achieving the foregoing ends a number of important features are incorporated in the machine in accordance with the invention. The rotary cam mentioned may be driven in a variety of different ways. It may be driven by suitable connections from the rotary hook shaft of the machine or it may be driven by independent connections from the main shaft in the base of the machine which also drives the hook shaft. When the cam carrying shaft is driven from the hook shaft this may be either through a toothed belt cooperating with toothed sprockets or it may be through appropriate gearing. A belt connection between the cam shaft and the hook shaft is generally preferred because it eliminates the noise incident to the operation of gearing. Also in the pre ferred embodiment of the invention, the arrangement is such that the cam carrying shaft is rotated at only half the angular speed of the hook shaft. Thus, in a machine in which the hook shaft is rotated through two revolutions for each revolution of the main shaft and for each reciprocation of the needle, the cam will be rotated only one revolution for each reciprocation of the needle. tions of the hook are idle so that no opening action is required during such revolutions. -However, certain advantages of the invention are obtained even when the cam carrying shaft is revolved at the. same angular speed as the hook shaft. The cam may be of substantially the same configuration regardless of whidh of the two.

mentioned speeds of rotation are imparted to it.

An important specific feature of the invention is the ad.

shaft and it, together with its supporting shaft, may

be adjusted angularly in relation to their driving means, and hence in relation to other driven parts of the machine,

such as the rotary hook. By virtue of these adjust-. ments, the timing of the action of the cam may be varied.

to suitvthe particular requirements of the work to be performed and the diametral adjustment of the cam makes possible a desirable variation in the extent of the opening action imparted by it to the bobbin carrier and also the amount of the clearance provided between it and the bobbin carrier when the needle loop is drawn between them. This brings about various advantages such as the elimination of the need for small tolerances in the production and assembly of the various parts, the compensation for wear of certain parts, and the adjustment of the opening action to conform, to best advantage, with the requirements of the stitching operation to be performed, depending, for example, upon the character of the threads employed in the production of a line of stitching.

As a further special feature of the invention, the rotary cam and its supporting and driving shaft are preferably so located in relation to the rotary hook carrying shaft and the throat plate of the machine, as well as other elements thereof, that the machine is capable of operation at very high speeds. Thus, the preferred location of the cam and its supporting and driving shaft insures proper passage of the needle thread loop, during high speed operation shoulders on the bobbin carrier and a fixed part of the.

machine, such as the throat plate, but also through the gap between the operating surface of the cam and a cooperating projection on the bobbin carrier. For extreme- 1y high speed operation of the machine it becomes important to space the second specified gap as far apart as possible from the in the direction 9f hook rotation,

As will be understood, alternate revolu-.

On the other hand, where conventional speeds of operation in the neighborhood of 4,000 stitches per minute are satisfactory, the indicated spacing of the two gaps may be less and the particular location of the cam and its supporting and'driving shaft becomes less important. It has been found possible under these circumstances to incorporate the new rotary cam device in hook units or saddles of the type heretofore employed, without substantial changes. The special location of the cam for high speed operation of the machine, on the other hand, requires substantial modification of previously existing hook saddles.

The invention is particularly suited for use in vertical axis hook machines having two rotary hooks cooperating with separate needles carried by a reciprocating needle.

bar. Units constructedin accordance with the invention are such as to make possible the relatively close spacing of the two lines ofstitching formed by the two needles and their cooperating vertical axis hooks. This is an important consideration since its adapts the invention for use in machines capable of producing either widely or closely spaced lines of stitching. The two units applied to a machine diifer from each other slightly, because of their right and left hand relationship, but in principle they are the same.

While the invention is disclosed herein as applied to a vertical axis hook it may also be applied to a horizontal axis hook. In a vertical axis hook unit the bobbin carrier usually receives the bobbin directly and is sometimes referred to as a bobbin basket. On the other hand, the conventional construction for a horizontal axis hook involves a bobbin case which holds the bobbin and is in turn inserted in a carrier or holder which bears the same relation to the rotating hook body as does the bobbin carrier of the vertical hook unit.

Other objects, features and advantages of the invention will appear from the detailed description of several embodiments of the invention which will now be given in.

conjunction with the accompanying drawings, in which:

Fig. l is a planview of a portion of the work supporting base'of a sewingmachine embodying the invention, certain cover plates for said base being removed;

Fig. 2 is a bottom plan view of the base portion of the machine, with the bottom closure plates for the hook units removed;

Fig. 3 is a detail view, in elevation, showing the upper end of the cam supporting. and rotating shaft;

Fig. 4 is a top plan view of the cam supporting shaft;

Fig. 5 is a detail view in plan of a form of cam that may be applied to the shaft;

Fig. 6 is a view, partly in elevation but largely in section taken along diiferent vertical planes, showing a vertical axis rotary hook unit embodying the invention in association with cooperating devices;

Fig. 7 is a bottom plan view of a portion of the work.

supporting base of a sewing machine embodying a modified form of the invention, certain closure plates being removed;

Fig. 8 is a side view of a throat plate embodied in the machine;

Fig. 9 is a bottom plan view of the throat plate;

Fig. 10 is an exploded perspective view of the parts constituting the rotary hook, with its rotary component, bobbin carrier and the like;

Fig. 11 is a transverse vertical sectional view through the work supporting base of the machine, showing. the work feeding mechanism therein;

Fig. 12 is a view, largely in top plan but with parts broken away and other parts shown in section, illustrating the relationship between the rotary. hook, the rotating cam and the throat plate of the machine;

' Fig. 13 is a view similar to Fig. 12 but illustrates the parts in a different relation, occuring at a different point in a cycle of operation;

Fig. 14 is a vertical sectional view taken alongthe line 14-14-ofFig-. 12;

Fig. 15 is a vertical sectional view taken along the line 1 5 -15 ofFig'. 13;

Fig. 16 is a vertical sectional view through the lower portion of a modified form of book unit embodying the invention, taken along the line 16-46 of Fig. 17;

Fig. 17 is a bottom plan view of the unit shown in Fig. 16 with a bottom closure plate for'the hook unit removed;

Fig. 18 is avertical. sectional view through. the unit shown in Figs: 16'and' 17', taken" along the line 1818 of Fig; 19 is a bottom plarrview of a'hookunitzsimilar'to that shown in Figs. 16-18 but with different gearingconnecting the hook shaft with the camsupporting shaft, the bottom closure plate of the unit'lieing removed;

Fig. 20 is a bottom planviewofthebase portion of a sewing machine embodying a modified form of the inventin in which the cam supporting shaft is driven from the mainrotary shaft in. the base, the bottom closures. forthe hook" units beingremoved;

' Fig. 21 is a vertical sectional view taken along the line Fig. 22 is a .vertical sectional view taken 2222ofFig; 20;"

' Fig; 23 is a vertical sectional view taken along the broken line'23-23ofFig. 20;,

.Fig. 24isa' top plan view of'a plurality of modified? hookun'its' mountedin the work supporting base of a sewing'machine, the illustrated units havingth'e bobbin basket? opening cam in a diiferentlocation in relation to the rotary hooks;

Fig; 25 is a detail view showing a feed dog liftingand lowering eccentric and a portion of the connected feed bar:

' Fig." 26is a vertical sectional view taken alongthe. line 26-26 of Fig; 24;

Fig. 27 is a bottom planview of a portion of one'of the hook units-embodiedin Fig. 24 with the bottom closure plate removed and the gearing in the bottom shown in broken lines;

' Fig. 28is' a" vertical sectional view taken along different vertical planesthrough the right hand portion of Fig,.24'; and

i Fig. 29 isa'plan view showing the relationship between" the two rotary hooks, their related rotary earns, the throat plate and the feed bar of a machine embodyingthe form'of the invention shown in Fig. 24.

The various forms .of' the invention illustrated in the accompanying drawings have been shown as applied to a sewing machine of the general character illustrated in the patent to Quist, No. 2,329,484, granted September 14, 1943, and the patent to Cottrell, No. 2,712,802, granted July 12, 1955. Thus, it will be understood that the machine comprises a main frame having a work supporting base, a vertical standard and an overhanging arm. A rotary drive shaft extends longitudinally of the base and' another rotary drive shaftextends longitudinally of the" overhanging arm, these shafts being interconnected for rotation in unison by gearing, or the like, in the vertical standard. In the work supporting base there is also provideda longitudinally-extending rock shaft adapted. to be rocked or oscillated by suitable connections from. the rotary drive shaft in the overhanging arm.

Referring now tothe drawings, there is shown in Fig.2 the work supporting base 10 of the machine. In this is mounted for rotation the main lower drive shaftll, the latter being journalled in bearing sleeves 12 and 13 carried by suitable lugs forming part of the frame. A rock shaft 14 extending longitudinally of the base portion of the frame is arranged to be driven, in the manner explained above, from the main rotary drive shaft in the overhanging arm. One of the rotary hook units embodied in the machine is designated generally at 15', this comprising a frame havinga clamping portion 16' arranged'to be clamped upon the bearing sleeve 12. The arrangement such that the unit-'maybe adjusted axially-along along the line the bearing sleeve 12 and clamped in any desired .set position. At its opposite side the unit is secured to the base portion of the frame by a screw 17 passing through an elongated slot in the frame of unit '15 and having threaded engagement with the base portion of the main frame. A second rotary hook unit designated generally at' 18 is of similar construction to unit 15 but has a slightly different relationship between certain of its parts, so that there is in effect provided a right-hand and a lefthand hook unit, both arranged to be driven directly from the shaft 11. The unit 18 has a clamping portion 19 arranged to be adjusted axially along the bearing sleeve 13. A screw 20 cooperating with a flange at the opposite side of the unit 18, provided with an elongated opening, serves to secure this side adjustably to the base portion of the main frame of the machine.

Referring now to Fig. 6, the unit 15 comprises a frame or saddle 21 having a lubricant containing enclosed housing portion and having upper and lower lateral extensions 22 and 23 in which certain parts are journaled. Thus, a hollow hook shaft 24 is journaled in suitable bushings carried by extensions 22 and 23, this shaft carrying a spiral gear 26 intermediate said extensions. The gear 26 is adapted to mesh with a spiral gear 27 (Fig. 2) secured to the rotary shaft 11 in a manner to permit its axial adjustment along the latter to conform with the adjustment of the hook' unit. Gears 26 and 27 are such that two revolutions are imparted to the shaft 24 for each revolution'of the shaft 11. At its upper end the shaft 24 carries a rotary hook 28 which, as best shown in Figs. 10, 12 and 13, is provided with a beak 28w adapted to seize a needle thread loop at the appropriate time in a stitch forming cycle. This needle thread loop is indicated at 29 in Fig. 6 and, as shown, extends downwardly from the right-hand one of a pair of needles 30-. It will be understood that the other needle shown cooperates in a similar manner with the rotary hook embodied in the unit 18. Within the rotary hook 28 is mounted a bobbin carrier or holder 3-1 (Fig. having a radially projecting rib cooperating with a groove or raceway in the body of the hook 28. A bobbin 32 is arranged to be carried by the holder 31. A portion of the raceway in the hook body is provided by a removable plate 33 secured by screws 34 to the main hook body. The arrangement is such, as will be explained, that the bobbin case holder 31 is restrained against rotation under the frictional drag of the hook body as the latter is revolved at high speed.

.- The means for restraining the bobbin holder against rotation with the hook body comprises a projection 35 extending laterally from a flange at the top of the holder. This projection fits into a gap 36 provided between downwardly extending ribs 37 and 3-8 on the undersurface of a throat plate 39 secured by screws or the like to the base of the main frame. Normally, the frictional drag tending to rotate the bobbin holder, will urge the projection 35 into engagement with the adjacent edge of the rib 37, as shown in Figs. 13 and 15. In order to make it possible to carry the upper leg of the needle thread loop 29 across the top of the bobbin holder, it is necessary to provide a gap between the projection 35 and the rib '37 at the appro priate time. This is indicated in Fig. 12. To accomplish this, the flange at the top ofthe bobbin holder is provided with a triangular projection 35a arranged to cooperate with a continuously revolving cam 40. The latter is so constructed and arranged as to act upon the projection 350 at the proper time in a cycle of stitch'formation to turn the bobbin holder in a direction counter to the frictional force applied thereto by the rotating hook. As shown in Figs. '12 and 14, this reverse movement of the bobbin holder is sufiicient to provide the desired gap between the shoulders on projection 35 and rib 37 for the passage of the needle thread loop but preferably not so great as to force the projection 35 into engagement with the rib 38. 39am 1 .1? i r o with an n a ed ope ng. 4.1

arranged to cooperate with a diametral rib 42 extending upwardly from the upper end of a rotary shaft 43. This shaft 8 is provided with an axially extending screw threaded opening 44 at its upper end with which cooperates a screw 45 for securing the cam 40 to the top of the shaft. The opening 44 divides the rib into two sections, as shown in Fig. 4. As will be seen, the arrangement is such that the position of the cam 40 in relation to the shaft 43 may be varied slightly in a diametral direct-ion to either increase or decrease the camming action of the cam 40 on the projection 35a of the bobbin holder. This adjustability of the cam eliminates the need for close tolerances in the production of various parts and also allows take up for wear and assurance that adequate clearance is provided between projection 35 and rib 37 to allow the needle thread loop to pass' through the gap in the manner explained. It also insures the provision of an appropriate gap between the periphery of the cam and the cooperating surface of the projection 35a at the proper time to permit the free passage of the needle thread loop between these parts.

For rotating the shaft 43 and cam 40, connections are provided from the hook shaft 24, as best shown in Figs. 2 and 6. These connections comprise a toothed sprocket 46 secured to the shaft 24 adjacent its lower end, a sprocket 47 secured to the shaft 43 adjacent its lower end and a toothed belt 48 interconnecting the sprockets for rotation in unison. In the arrangement disclosed in Figs. 2 and 6 the sprocket 47 is of twice the diameter of sprocket 46 so that shaft 43 is rotated at only half the angular speed of shaft 24. This provides for a single revolution of the cam 40 for each two revolutions of the hook body 28, one of which .is an idle revolution, as will be understood. It should be noted that the driving connection between the shafts24 and 43 is such that these are both revolved in the same direction. This is indicated by the arrows in Figs. 12 and 13, the arrangement being such that the frictional force applied by the cam to the cooperating surface of the projection 35w assists the camming action on the latter in turning the bobbin carrier against the frictional drag imparted by the rotating hook body 28. I The form of the cam 40 and its angular position on the shaft 43, in relation to the angular position of the beak 28a of the hook body 28 at any instant, are such as to bring about the proper timing of the camming action of cam 40 on the bobbin holder depicted in Figs. 12 and 13. To insure the proper timing of this action, and to enable variation of the angular relationship mentioned, the sprocket 47 is secured tothe shaft 43 by means of a set screw 4711. By loosening the latter, the shaft 43 and cam 40 may be turned without causing'rotation of either of the sprockets or the shaft 24. In way appropriate timing may be insured for a variety of different seaming operations. 1 In Fig. 7 there is shown a connection between the shafts 24 and 43 which brings about rotation of shaft 43 at the same angular speed as shaft 24. For this purpose a sprocket 49 secured to the shaft 24 and [a sprocket 50 secured to the shaft 43 are of equal'diaimv eter and are interconnected by a toothed belt 51 to bring about the result stated. With this arrangement it will be understood that the cam '40 will act upon the pro jec-tion 35a of the bobbin holder on each revolution of the hook body 28 and hence twice for each reciproa cation of the needle bar. Since one of these actions of the cam 40- is an idle one, it is considered preferable, in general, to employ the arrangement disclosed in Fig. 2;

'It will 'be noted by reference to Fig. 13 that that portion of the cam 40 which is opposite the projection 35a on the bobbin holder, shortly after the cam has shifted the bobbin holder in the manner indicated in Fig. 12 and for a suitable period thereafter, is cut away as indicated at 4011. This provides a clearance between: hep oi c 35 he am, th eh hen edlg 7 thread loop 29 may be readily passed as the hook beak reaches its loop shedding position. It is important that this gap be provided, in the embodiment of the inven tion now being described, shortly after the gap between projection 35 and rib 37 has been opened up for the passage of the upper leg of the needle thread loop, since this loop is very quickly carried into the region of the cam 40 after this has occurred. The provision of this cutaway portion of the periphery of cam 40 is particularly desirable when the cam is located in the position shown, for the embodiment of Figs. 1 to 15, in relation to the hook body and the throat plate. As will be explained in connection with another embodiment of the invention, the cutting away of a substantial arc of the periphery of the cam is not necessary when the cam is located in a different position in relation to the parts mentioned.

: Unit 18 of the machine illustrated differs only slightly from unit 15 above described and functions in substantially the same manner. Certain differences are, however, necessary in the construction of the frame of the unit and the relationship of various parts. It should be .noted in this connection that the two hook shafts 24,. one for each of the two units, have their axes in the same vertical plane transverse to the line of stitch formation and both of these shafts are revolved in the same direction. As a result of this, the hook beak of the unit 15 is arranged to seize the needle thread loop 29 while the beak is moving in the direction of feed of the work while the hook beak of the unit 18 is arranged to .travel at this time ina direction counter to the direction of feed of the work. This, of course, means that the cams 41} for the twounits must turn the bobbin holders in the same direction about their axes to provide the gap between the projection 35 and the cooperating shoulder on the throat plate at the proper time, but in doing so the projections are actually moved in reverse directions, i.e., one in the direction of feed and the other counter to the direction of feed. This necessitates a slightly different location of the ribs on the throat plate 39 which cooperate with the projections 35 of the two bobbin holders, as shown in Fig. 9. The projection 35 of the bobbin holder for unit 18 is urged by the frictional drag of the rotating hook body against the adjacent shoulder on the rib 38a and the projection is shifted by the cam toward, but not quite against, the adjacent shoulder of the rib 37a.

. .Suitable work feeding mechanism is provided for advancing the work along the throat plate in the course of stitchformation. It is important that this be constructed and arranged in such a manner as not to interfere with the above-described adjustment of the positions of the two hook units toward and away from each other to bring about either a relatively close spacing of the two lines of stitching formed thereby or a relatively wide spacing of these. lines of stitching. For this purpose the work feeding mechanism, which is interposedbetween the two units 1 and 18, may suitably be of the character disclosed in the above-mentioned Quist and Cottrell patents. It may comprise a feed dog 52 (Fig. 11) having a downwardly extending shank 53 arranged to be secured by a screw 54, in an appropriately adjusted vertical position, in a channel formation 55 provided in a feed bar 56. The vertical position of the feed dog 52 may be readily and accurately adjusted by means of a screw 57 cooperating with the lower end of the shank 53 of the feed dog. In the course of such adjustment the screw 54 will be loosened and then retightened when the adjustment is accomplished. At its rearward end (to the left in Fig. 11) the feed bar 56 is pivotally connected by means of a pin 58 with the lower end ofa pitman 59 having a strap surrounding an eccentrio-'60 secured to the rotary shaft 11. It will be apparent that through this connection the indicated end of the feed bar will be lifted and lowered upon each revolution of the shaft 11 and thus lift and lower the feed dog in relation to the openings in the throat plate 29. At its opposite end the feed bar 56 is pivotally mounted, by means of a rod or shaft 61, on the upper end of a feed rocker 62. The latter is secured to the rock shaft 14 which, as previously explained, is rocked by connections from the top rotary shaft. As shown in the Quist patent mentioned, the connections for this purpose may be coordinated with connections for imparting a needle feed action to the needle bar of the machine. Feed and return movements are thus imparted to the feed dog. As will be seen from Figs. 2, 6 and 7, the construction of the hook units 15 and 18 and of the feed mechanism just described is such that the two rotary hook bodies may be brought quite closely together to make possible the formation of two closely spaced lines of lockstitches.

Turning now to Figs. 16, 17 and 18, there is disclosed a modified form of book unit or saddle embodying the rotary cam construction of the invention. In this form of the invention a spiral gear 63 (Fig. 18) secured to the rotary drive shaft 11 in the base of the frame cooperates with a spiral gear 64 secured to a hook carrying shaft 65 of the unit. The latter at its upper end carries the rotary component 65a of the hook. Adjacent its lower end the shaft 65 has secured thereto a gear 66 which meshes with an idler gear 67 suitably journaled in the frameof the unit. This idler gear in turn meshes with a gear 68 of double the diameter of gear =66. Gear 68 is secured to the lower end of a shaft 69 which carries at its upper end a cam 70 which may be similar to and mounted in the same manner as the cam '40 of the first embodiment. It will be understood that gearing 63, 64 is such as to rotate the hook at double the angular speed of the shaft 11. In turn the gearing 66, 67 and 68 is such as to rotate the shaft 69 and the cam 70 at half of the angular speed of the rotary hook and hence at the same angular speed as the shaft 11. The construction of the hook and the action of the cam 70' thereon may be the same as described in relation to Figs. 1-15, inclusive.

In Fig. 19 there is shown a construction which may be the same as that shown in Figs. 16-18 except for the provision of a different gearing between the hook shaft 65 and the cam supporting and rotating shaft 69. In this modified construction the gear 66 secured to the hook shaft meshes with an idler gear 71 positioned somewhat differently from the idler 67 above described. Gear 71 meshes with a gear 72 having a diameter equal to that of gear 66. Gear 72 is secured to the lower end of shaft 69 and serves to rot-ate the same in the same direction as shaft 65 is being rotated and at the same angular speed as the latter. In this embodiment of the invention thecam 70 will be given a complete revolution for each revolution of the hook body 65a. In other respects the construction may be the same as previously described.

Figs. 20-23 illustrate a further modification of the invention. In this form, the means for rotating the cam which opens the bobbin basket or carrier is driven by connections from the main rotary shaft in the base independently of the means for driving the rotary hook. Thus, .as shown, the machine is provided with a rotary drive shaft 73 journaled in bearing sleeves 74 and 75 carried by the base of the frame. Shaft 73- corresponds with shaft 11 of the first embodiment.- A pair of hook units or saddles 76 and 77 is provided, one being mounted in the same manner as the unit 15 of Fig. 2 and the other mounted in the same manner as unit 18 of Fig. 2. Secured to the shaft 73 are two spiral gears 78, one for driving the hook carrying shaft in each of the units 76 and 77. These gears mesh with spiral gears 79 secured to the respective hook shafts 80 of the two units. Shaft 80 of each unit carries at its upper end a rotary hook 81 of the same construction described in relation to the first embodiment. Adjacent each of the spiral gears 78 there is secured to the shaft 73 or formed integrally therewith, asm-aller spiral gear 82 which meshes with a spiral gear 83' of the related hook unit. For the unit 76, show-11in Fig. 22, the gear 83 is secured to a shaft 84 which carries at its upper end a cam 85 which may be of the same construction and mounted in the same manner as the cam 40 previously described. For the unit 77 the gear 83 is secured to a shaft 84a (Fig. 21) which at its lower end carries a toothed sprocket 86. The latter is connected by a toothed belt 87 with a toothed sprocket 88 secured to the lower end of a shaft 89 which is mounted in the hook unit or saddle and which carries a cam 90* at its upper end. This cam may likewise be of the same character as cam 40 and may be mounted on the shaft in the same manner. The gearing described is such that while each hook shaft 80 is rotated at double the angular speed of the shaft 73, the shafts 84, 84a and 89 will be driven at the same angular speed as the shaft 73. The construction and mode of operation of the form of the invention just described is in other respects just the same as the form shown in Figs. 1-15, inclusive. It will be appreciated that, if desired, the connections from the shaft 73 to the shafts 84 and 89 could be such that the latter would rotate at double the angular speed of the shaft 73 and thus at the same angular speed as the rotary hook carrying shafts 80.

In each of the foregoing embodiments it will be noted that the relationship of the hook shaft to the rotary cam shaft of the several units is the same. This relationship is such that it acts on the projection 35a of the top flange of the bobbin basket or carrier at a point about 135 back of the point at which the hook beak seizes the needle thread loop. For machines intended to be driven at especially high speed it has been found desirable to locate the point of contact of the cam with the indicated projection on the bobbin basket somewhat closer to the point at which the hook beak seizes the needle thread loop, preferably along a line somewhat less than 90 back of the latter point. Such an arrangement is shown in Figs. 24-29. It allows a somewhat greater part of a revolution of the hook in which to develop a gap for the passage of the needle thread loop between the cam and the basket projection on which it acts, after the cam has completed its function of turning the basket to open up the gap between the restraining shoulders which prevent the basket from rotating with the hook body. It also enables the use of a cam of somewhat different configuration, i.e., one having a smooth periphery with only one shoulder at the point between the maximum and minimum radii of the cam.

Referring now to Figs. 2429, inclusive, there is shown at 91 the main rotary drive shaft in the base of the frame, this shaft corresponding with shaft 11 of the first embodiment. It is journaled in bearing sleeves 92 and 93 carried by the frame. Hook units or saddles 94 and 95 are carried by the frame in the same manner as the units 15 and 18 so that they may be adjusted toward and away from the line of stitch formation. Two spiral gears 96 are secured to the shaft 91 in a manner to permit their axial adjustment along the shaft to correspond with the location of the units 94 and 95. Each gear 96 meshes with a spiral gear 97 (Fig. 26) secured to a shaft 98 journaled for rotation about a vertical axis in the related unit and arranged to carry a rotary hook of the character above described. A gear 99 secured to the shaft 98 adjacent its lower end meshes with an idler gear 100 which is suitably journaled in the hook unit and which in turn meshes with a gear 101 secured to the lower end of a vertical shaft 102 which carries a cam 103 at its upper end. The preferred contour of cam 103 is shown in Fig. 29. It is arranged to cooperate with a triangular projection 104 at the top of the bobbin basket. It will be noted that when the projection 104 is permitted to ride from the high to the low point of the cam, the loop seizing beak 105 of the hook body is about 120 away from the projection 104. Also, it will be noted that the axis of the shaft 102 and the cam 103 is located in a vertical plane through the axis of the hook shaft that is less than back of the vertical plane which contains the axis of the hook shaft and the point at which the hook beak seizes the needle thread loop. These relationships insure adequate clearance between the projection 104 and the surface of cam 103 at the time the needle thread loop is being drawn from the hook by the usual take up mechanism and must be passed between the projection 104 and cam 103. The means for restraining rotation of the" bobbin basket by the frictional drag of the rotating hook body may be the same as in the first embodiment and.

may comprise a projection 106 at the top of the basket arranged to fit into an opening provided between down-,

wardly extending ribs 107 and 108 on the throat plate 1071). Considering the uppermost hook shown in Fig. 29, the projection 106 is normally urged against the adjacent shoulder of rib 108 by the frictional drag mentioned, and it is carried away from said shoulder and toward, but not quite into engagement with, a shoulder at the adjacent end of the rib 107 by the action of the cam 103 at the proper time. Fig. 29, the projection 106 is urged by the frictional drag of the hook body toward the rib 107a and it is urged by the cam toward the rib 108a.

To enable adjustment of the units 94 and into a. position in which they are relatively close to each otherand thus provide for the formation of two closely spaced lines of stitching, a feed bar 110 of slightly different shape from that designated 56 in the first embodiment is provided. Feed bar 110 is rockably mounted, by means of a sleeve portion 111 in the upper ends of arms 109 of a feed rocker, similar to member 62 shown in Figs. 2

and 11, which is arranged to be rocked by the oscillation of a shaft similar to the shaft 14 of Fig. 2. This serves to impart the feed and return movements to the feed dog.

The latter, as shown in Fig. 26, has a shank 113 arranged for vertical adjustment in a channel 112 provided in the feed bar 110 at an intermediate point. The active portion of the feed dog is indicated at 114 and the arrangement is such that the relationship of this to the throat plate of the machine may be varied by the loosening of a. clamping screw 115 which enables adjustment of the shank 113 of the feed dog in the channel 112. In front of the feed dog carrying channel 112 of the bar 110' the latter is provided with a reversely curved portion 116 (Fig. 24') and the extreme forward end of the bar is pivotally connected by a pin 117 with a pitman 118 having a strap portion surrounding an eccentric 119 secured to the shaft 91. Through this connection the lifting and lowering movements are imparted to the feed dog;

the two hook units 94 and 95 into closely spaced relationship.

I claim:

1. In a lockstitch sewing machine a frame having a work supporting base, a rotary drive shaft extending longitudinally of said base, a hook shaft, connections from said drive shaft to said hook shaft for rotating the latter at twice the angular speed of the drive shaft, a rotary hook carried by said hook shaft, said hook having a rotary component secured to said hook shaft for rotation there with and a bobbin carrier journaled within said rotary component, said rotary component having a thread loopseizing beak, said carrier and said frame having cooperating shoulders for restraining said carrier against rotation with said rotary component in the normal stitch forming operation of the latter, a rotary cam adjacent said bobbin carrier, said bobbin carrier having a surface thereon arranged to be engaged by said cam and acted upon by the latter to cause turning of said carrier counter to the direction of rotation of said rotary component to thereby disengage said shoulders to enable the passage of a branch of the thread loop therebetween, and connections for For the hook at the bottom of 

